Many banks offer this service without any third party. I don't generally see it advertised a lot, I assume because it's confusing to people who have no interest

Many banks offer this service without any third party. I don't generally see it advertised a lot, I assume because it's confusing to people who have no interest in it, but you can look up something like "virtual credit card" or "temporary credit card number" and probably find a bank offering it. The very crude answer is to get a prepaid card and load it with enough to cover each purchase, then toss it as soon as it gets misused. Which works, but doesn't sound worth the hassle unless you seriously expect a bad outcome.